The invention relates to an internal-combustion engine comprising an intake system consisting of a chamber having an intake connection and individual suction pipes which are connected with a cylinder head and which lead into the individual cylinders, the interior of the chamber being connected to a pollutant reducing system which comprises at least one of the systems, such as a housing venting system, an auxiliary-air feeding system, a fuel vapor catch system and an exhaust gas return system.
Because of a variable air flow rate to the individual cylinders, airborne noises occur in an intake system of an internal-combustion engine which may radiate toward the outside. Furthermore, a back and forth movement of the pistons in the cylinders of the internal-combustion engine is accompanied by a volume change of the air supply to the individual engine cylinders and the exhaust system. In this case, the gases move in the above-mentioned pipes with pressure fluctuations whose magnitude and direction is determined by the engine operation. These pressure fluctuations of the gases are the cause of gas-dynamic and acoustic phenomena which under certain conditions may have a negative influence on the engine operation. In particular, the volumes of the pipes determine the sound radiation which is generated by the parts which connect the gas pipes with the outside air, such as the inlet opening of the air intake of the air purifier or the outlet opening of the exhaust pipes. The same reasons cause a discontinuity of the gas flows in the pipes of the pollutant reducing system which may considerably impair its function.
It is an object of the invention to provide an intake system for an internal-combustion engine which, in addition to reducing airborne noises, also causes a decrease of the emission of pollutants.
According to the invention, this object is achieved by means of an arrangement wherein an intake pipe, which projects into the chamber of the intake system, is fastened to the intake connection, which intake pipe has a mouth opening approximately in a plane between two central individual suction pipes and, and a pipe connection leads into the interior of the chamber which connects the systems to of the pollutant reducing system.
By means of the arrangement of an intake pipe which projects into the chamber interior of the intake system and which is connected with the intake connection of the chamber, a noise reduction is essentially achieved, in which case a significant reduction of the emission of pollutants is achieved as a result of this pipe, in connection with a connection piece which branches off a pollutant reducing system and which also leads into the interior of the chamber or of the pipe.
For this purpose, the mouth opening of the connection piece is arranged at a defined distance from the center of gravity of the interior volume of the chamber of the intake system.
Advantageously, the connection piece may also have an oblique mouth opening which causes an increased mixing of the flows from the pollutant reducing system and from the intake connection.
A contraction of the pipe in the manner of a diffuser in the area of the entering of the pipe connection into the intake pipe causes, in the area of the contraction, an increase of the flow velocity of the gas flow from the intake connection, whereby an additional gas flow from the pollutant reducing system is generated and a mixing effect is caused.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.